<!doctype html>
<html lang="zh-CN">
  <head>
    <!-- 必须的 meta 标签 -->
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">

    <!-- Bootstrap 的 CSS 文件 -->
    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.6.2/dist/css/bootstrap.min.css" integrity="sha384-xOolHFLEh07PJGoPkLv1IbcEPTNtaed2xpHsD9ESMhqIYd0nLMwNLD69Npy4HI+N" crossorigin="anonymous">
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    <title>Hello, world!</title>
  </head>
  <body>
    <h1>Hello, world!</h1>

    <!-- JavaScript 文件是可选的。从以下两种建议中选择一个即可！ -->

    <!-- 选项 1：jQuery 和 Bootstrap 集成包（集成了 Popper） -->
	<!--
    <script src="https://cdn.jsdelivr.net/npm/jquery@3.5.1/dist/jquery.slim.min.js" integrity="sha384-DfXdz2htPH0lsSSs5nCTpuj/zy4C+OGpamoFVy38MVBnE+IbbVYUew+OrCXaRkfj" crossorigin="anonymous"></script>
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	-->
    <!-- 选项 2：Popper 和 Bootstrap 的 JS 插件各自独立 -->
    <!--
    <script src="https://cdn.jsdelivr.net/npm/jquery@3.5.1/dist/jquery.slim.min.js" integrity="sha384-DfXdz2htPH0lsSSs5nCTpuj/zy4C+OGpamoFVy38MVBnE+IbbVYUew+OrCXaRkfj" crossorigin="anonymous"></script>
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    <script src="https://cdn.jsdelivr.net/npm/bootstrap@4.6.2/dist/js/bootstrap.min.js" integrity="sha384-Lge2E2XotzMiwH69/MXB72yLpwyENMiOKX8zS8Qo7LDCvaBIWGL+GlRQEKIpYR04" crossorigin="anonymous"></script>
    -->
	<nav class="navbar navbar-expand-lg navbar-light bg-light">
	  <a class="navbar-brand" href="#">Navbar</a>
	  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
	    <span class="navbar-toggler-icon"></span>
	  </button>
	
	  <div class="collapse navbar-collapse" id="navbarSupportedContent">
	    <ul class="navbar-nav mr-auto">
	      <li class="nav-item active">
	        <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
	      </li>
	      <li class="nav-item">
	        <a class="nav-link" href="#">Link</a>
	      </li>
	      <li class="nav-item dropdown">
	        <a class="nav-link dropdown-toggle" href="#" role="button" data-toggle="dropdown" aria-expanded="false">
	          Dropdown
	        </a>
	        <div class="dropdown-menu">
	          <a class="dropdown-item" href="#">Action</a>
	          <a class="dropdown-item" href="#">Another action</a>
	          <div class="dropdown-divider"></div>
	          <a class="dropdown-item" href="#">Something else here</a>
	        </div>
	      </li>
	      <li class="nav-item">
	        <a class="nav-link disabled">Disabled</a>
	      </li>
	    </ul>
	    <form class="form-inline my-2 my-lg-0">
	      <input class="form-control mr-sm-2" type="search" placeholder="Search" aria-label="Search">
	      <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
	    </form>
	  </div>
	</nav>
  </body>
</html>